The present invention relates to breathing apparatus and more particularly to respirators for supplying breathable gas to a patient or other user.
While of general application, the invention is particularly well suited for use with respirators of the generator type. As is well known, such respirators commonly include a user circuit having a face mask or other breathing apparatus and insufflation and exhalation lines connected to the mask. The insufflation line communicates via an insufflation valve with a compressed gas generator, while the exhalation line communicates with the atmosphere via an exhalation valve. The alternate opening and closing of these valves marks successive insufflation and exhalation phases, the insufflation phase beginning with the opening of the insufflation valve and the simultaneous closing of the exhalation valve, and the exhalation phase beginning with the opening of the exhalation valve and the simultaneous closing of the insufflation valve.
There are at the present time large numbers of such respirators on the market. In some of the respirators currently available the gas generator insufflates the user directly with compressed breathable gas, while in other respirators the insufflation of the breathable gas is performed mechanically by a reservoir which forms a storage container. The respirators are employed, inter alia, to supply breathable gas to sick persons, and they are useful in the home, hospitals, in first aid and so on.
Respirators of the type heretofore employed have exhibited a number of disadvantages. For example, in many prior respirators of the generator type, the user occasionally was subjected to unwanted pressure fluctuations during the insufflation phase, resulting in discomfort and other deleterious effects. In addition, such prior systems frequently required compressors of unnecessarily high capacity in order to accommodate instantaneous input requirements of the user circuit. These and other disadvantages greatly restricted the versatility and reliability of the prior respirators.